Chain saw guide bar with liquid spray device

ABSTRACT

Chain saw guide bar and method of using a guide bar for spraying liquid on a sawn surface through a plurality of orifices formed in a guide bar side plate. The liquid is introduced into an inlet portion of a passage formed in a center plate of the guide bar and is conducted forwardly to the orifices. The liquid is sprayed from the orifices at equal pressures, and in spray directions having a component oriented parallel to a centerline of the guide bar. Thus, by adjusting the velocity of the sprayed liquid, the length dimension of the area sprayed can be adjusted.

BACKGROUND

It is previously known that chain saw guide bars can be provided withchannels and orifices to spray the sawn surface with liquid, such aspaint for colour coding or fungicide as described in patent SE7611822-3, or both. Such guide bars are commonly used on vehicle-bornchain saws.

For colour coding it is important to get distinct markings, and eachliquid channel then has generally just one orifice. For sprayingfungicide, it is important to cover a major part of the sawn surface,but at the same time not to spray outside that surface, which wouldconstitute excessive waste of liquid and an environmental hazard.

In U.S. Pat. No. 5,143,131 was described a guide bar design where theliquid channel has a multitude of orifices, all of which need not beopen simultaneously. The choice of which orifices are to be open isregulated with slideable metal strips with orifices forming a differentpattern from the orifices in the sideplate of the guide bar. The stripsare moved with an external device, such as a hydraulic actuator on theunderside of the guide bar, until the desired number of orificescoincide between the strip and the sideplate. Such a device isvulnerable, however, due to the slideable strips and the unprotectedlocation of the hydraulic actuator. It is also difficult to have areliable indication at the operator's cab of how large a surface isbeing sprayed.

The present invention concerns a chain saw guide bar for fungicidespraying, where the extent of the sprayed area can be varied in relationto the size of the sawn surface, without small movable parts and withoutactuators at the guide bar, and where it is simple to indicate for theoperator how large an area is sprayed.

DESCRIPTION OF THE INVENTION

A guide bar according to the invention is provided with orifices whichgive the liquid a velocity component along the plane of the guide bar,not only vertical to the plane. Such orifices are described in thepatent SE 9300180-8, where they were utilized to make liquid spray fromorifices near the bar centerline hit the cut surface close to the edgeof the bar, to allow return of the bar as soon as the saw chain hasfully penetrated the tree trunk, with a smallar angular movement thanotherwise. According to that patent the liquid is given a velocitycomponent across the bar from the centerline towards the edge.

In a guide bar according to invention, a plurality of orifices arelocated to give the liquid a velocity component parallel to the barcenterline. The size of this velocity component and thus the width ofthe sprayed area measured along the bar depends on the liquid pressurein the channels of the bar before the orifices.

The orifices are located adjacent to a pressure equalizing chamber inthe guide bar, to make the spray velocity independent of the liquid flowwithin the channels. By measuring the liquid pressure at a pump orpressure vessel in the operator's cab, the operator can judge the widthof the sprayed area. The spraying occurs during angular motion of thebar while sawing, and the pressure may be automatically controlled inrelation to the position of the gripping arms of the machine holding thetree, this position indicating the diameter of the tree.

BRIEF DESCRIPTION OF THE DRAWINGS

A guide bar with spray orifices in one sideplate according to theinvention is shown in FIG. 1 in a view from below, and in FIG. 2 as across section through the pressure equalizing chamber. If desired, thebar can be made reversible and symmetrical with two pressure chambersand orifices in both sideplates.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The guide bar comprises two sideplates (11,12) and one center plate (13)joined by welding, brazing or adhesive. A liquid channel (14) is made asa cut-out in the center plate (13) to convey the liquid from a supplyhole (15) near the clamping end (20) of the guide bar to a pressureequalizing chamber (16) with a larger cross section than the channel(14). This makes the velocity of the liquid within the chamber (16) muchlower than in the channel (14). The spray velocity from all orifices isthen equal, and dependent only on the pressure.

In the sideplate (11) there are orifices (17). The channel (14) and thepressure equalizing chamber (16) together form a liquid-conductingpassage leading to the orifices. Only a minor part (18) of the areaalong the edge of each orifice overlaps the pressure equalizing chamber(16). The orifices are large enough to be blanked in the same operationas the sideplate contour. The pressure equalizing chamber (16) has aconvex contour facing the guide bar edge. This orients the overlappingparts of the orifices in such directions, that liquid sprayed from theorifices closest to the guide bar nose (19) has a velocity componenttowards the nose, and liquid sprayed from the orifices closest to theclamping end (20) has a velocity component towards the clamping end. Anequivalent effect can also be achieved by drilling smaller orificesobliquely through through the sideplates, but this is more difficult andliable to clog.

With low liquid pressure the spray will not reach far outside the widthof the chamber (16) and the liquid quantity will be limited. With a highliquid pressure the spray will reach a wider area and the liquidconsumption will be higher.

The liquids used to protect the sawn surfaces, primarily the remainingstumps, from fungal infection, is either chemicals such as urea, orwater suspensions of spores of harmless fungi which are antagonists orcompetitors to the harmful fungi. Pigments may be added to verify theliquid flow and to mark which surfaces have been treated.

I claim:
 1. A guide bar adapted for use in a vehicle-borne chain saw forspraying liquid onto a sawn surface, the guide bar having a longitudinalcenterline extending between front and rear ends of the guide bar, theguide bar comprising two side plates and a center plate disposedtherebetween, the center plate including a cut-out formed in at leastone side thereof, the cut-out defining a passage having inlet and outletportions, the inlet portion disposed adjacent the rear end of the guidebar for receiving a liquid to be sprayed, at least one of the sideplates including spray orifices communicating with the outlet portion ofthe passage for spraying liquid received therefrom, at least some of theorifices arranged such that a spray direction thereof has a componentextending parallel to the centerline of the guide bar.
 2. The guide baraccording to claim 1 wherein the passage includes a channel extendingfrom the inlet portion, and an enlarged equalizing chamber forming theoutlet portion of the passage, the equalizing chamber having a largercross section than the channel, the orifices communicating directly withthe equalizing chamber.
 3. The guide bar according to claim 2 whereinthe at least one side plate includes an inner surface facing the centerplate, said at least some orifices being arranged such that only aportion of their respective cross-sectional areas overlaps the pressureequalizing chamber.
 4. The guide bar according to claim 3 wherein saidat least some orifices constitute all of the orifices.
 5. The guide baraccording to claim 4 wherein an edge portion of the pressure equalizingchamber protrudes convexly toward an edge of the guide bar, the orificescommunicating with the pressure equalizing chamber along the convex edgeportion thereof.
 6. The guide bar according to claim 2 wherein anothercut-out is formed in another side of the center plate, and such otherside plate includes orifices communicating with the other cut-out forspraying liquid.
 7. A method of spraying liquid from a vehicle-bornechain saw onto a sawn surface comprising the steps of: introducing theliquid under pressure into an inlet portion of a passage formed in aguide bar of the chain saw, conducting the liquid forwardly to an outletportion of the passage, spraying the liquid outwardly through orificesformed in at least one side of the guide bar such that the spraydirection of the liquid from at least some of the orifices has acomponent extending substantially parallel to a centerline of the guidebar.
 8. The method according to claim 7 wherein said at least someorifices constitute all of the orifices.
 9. The method according toclaim 7 wherein the liquid is conducted through a channel of the passageto an enlarged pressure equalizing chamber which communicates thechannel with all of the orifices.